We propose to prepare the cyclic pentapeptide residue of actinomycin D (AM D) in sufficient quantities for condensation with several chromophores other than those of AM D. The synthesis of a homolog of AM D in which the sarcosine moiety is replaced by N-ethylglycine will be completed. Complexes of the new compounds with DNA will be studied by spectroscopic and physicochemical means to determine their binding parameters. Nucleic acid synthesis inhibition by these drugs will be assayed in L1210 cell culture. When possible, in vivo testing will be initiated.